Squamous Cell Carcinoma of the Breast

John Han-Chih Chang, MD and Kenneth Blank, MD
Last Modified: November 1, 2001

Dear OncoLink "Ask the Experts,"
Please send information on squamous cell carcinoma of the breast. Anything you could tell us would help.
BC

John Han-Chih Chang, MD and Kenneth Blank, MD, Editorial Assistants for Oncolink, respond:

Dear BC,
Thank you for your interest and question.

Not much is published on squamous cell carcinomas of the breast due to its rarity. Some believe it is a separate histology from ductal carcinoma, but others feel that it is part of a spectrum of squamous metaplasia that can occur with ductal cancers of the breast.

Diagnostically, little distinguishes squamous cell cancers of the breast from all others. In 1996, there was some data out of Princess Margaret Hospital on 19 patients with pure squamous cell carcinomas of the breast. Only 5 were available for full evaluation of their charts, pathology and radiology records. Of those five, the mean age of the patients was 55, with the tumor size average of 5 cm. These lesions were indistinguishable from ductal carcinomas on mammogram. There was a suggestion that some of the squamous cell carcinomas demonstrated more necrosis, which may appear more cystic on ultrasound than ductal carcinomas. They concluded that there was no difference in the diagnostic aspects regarding this rare histology.

Because of the fact that it is rare, risk factors for squamous cell breast cancer are not defined any different than for ductal carcinoma. As an aside, two case reports published did reveal that there have been cases (one each) of this rare histology being found in breast cancers after treatment for Hodgkin's disease or after breast augmentation.

Some have suggested a poor prognosis with this histology, but others state that stage for stage there is no difference in outcome. The number of patients with squamous cell histology is too low to make a definitive statement on the subject. As a rule, this type of breast cancer is treated no different than ductal or lobular carcinomas of the breast with comparable outcomes.